Solution:Concept- Non-metals are the elements found on the right of the periodic table (except Hydrogen). They are capable of forming negative ions because of their high electronegativity compared to metals.
They usually have 4,5,6, or 7 valence electrons.
Now, few non-metals are solids, few are liquids and few are gaseous.
The solid non-metals include carbon, iodine, and sulphur.
The only non-metal that exists as liquid is the halogen bromine. It occurs as a liquid at room temperature due to stronger intermolecular forces than other halogens like fluorine and chlorine.
Most non-metals exist in gaseous state naturally and they include gases oxygen, nitrogen, chlorine etc.
Thus, bromine is the liquid non-metal.
Hence, the correct option is (3).